The epidermal growth factor receptor (EGFR, Erb-B1) belongs to a family of proteins, involved in the proliferation of normal and malignant cells (Artega, C. L., J. Clin Oncol 19, 2001, 32-40). Overexpression of Epidermal Growth Factor Receptor (EGFR) is present in at least 70% of human cancers (Seymour, L. K., Curr Drug Targets 2, 2001, 117-133) such as, non-small cell lung carcinomas (NSCLC), breast cancers, gliomas, squamous cell carcinoma of the head and neck, and prostate cancer (Raymond et al., Drugs 60 Suppl 1, 2000, discussion 41-2; Salomon et al., Crit. Rev Oncol Hematol 19, 1995, 183-232; Voldborg et al., Ann Oncol 8, 1997, 1197-1206). The EGFR-TK is therefore widely recognized as an attractive target for the design and development of compounds that can specifically bind and inhibit the tyrosine kinase activity and its signal transduction pathway in cancer cells, and thus can serve as either diagnostic or therapeutic agents. For example, the EGFR tyrosine kinase (EGFR-TK) reversible inhibitor, TARCEVA®, is recently approved by the FDA for treatment of NSCLC and advanced pancreatic cancer. Other anti-EGFR targeted molecules have also been approved such as IRESSA®.

Despite the early success of Tarceva, it has become clear that selectively targeting individual kinases can lead to the development of drug resistant tumors. Cells that have developed mutations within the drug/kinase binding pocket display a growth advantage in the presence of drug eventually leading to disease progression. Accordingly, the discovery and development of new molecules to target such kinases may be important to treat patients that have already developed resistance to current therapeutic molecules.